The present invention is directed to bicycle pedals with cleat clamping mechanisms and, more particularly, to a bicycle pedal having a cleat clamping mechanism which has different clamping forces for engaging and disengaging the cleat.
U.S. Pat. No. 4,928,549 shows a conventional bicycle pedal with a cleat clamping mechanism for engaging a cleat attached to a sole of a bicycling shoe. The pedal includes a horizontally-oriented U-shaped front clamping member disposed on the front of the pedal for engaging a front projection of the cleat. An inverted L-shaped rear clamping member is pivotably connected to the rear of the pedal for engaging a rear projection of the cleat, and a spring biases the rear clamping member forward toward the pedal body. The upper surface of the rear clamping member has a vertically inclined portion which cooperates with the cleat when the cleat is to be engaged with the pedal, and inner side surfaces of the rear clamping member have respective horizontally inclined portions which cooperate with the cleat when the cleat is to be disengaged from the pedal.
In operation, the rider inserts the front cleat projection into the horizontally-oriented U-shaped front clamping member and presses the rear cleat projection downward on the upper surface of the rear clamping member. The rear cleat projection presses against the vertically inclined portion of the upper surface of the rear clamping member, thus causing the rear clamping member to pivot away from the pedal body against the biasing force of the spring. After the rear cleat projection passes below the edge of the rear clamping member, the rear clamping member pivots forward toward the pedal body in accordance with the biasing force of the spring, thus engaging the rear cleat projection. As a result, the cleat now is firmly clamped by the front clamping member and rear clamping member. To disengage the cleat from the pedal, the rider rotates his or her foot around an axis perpendicular to the pedal surface. This causes the rear cleat projection to press against one of the horizontally inclined portions of the rear clamping member, thus causing the rear clamping member to pivot away from the pedal body against the biasing force of the spring. The cleat is released from the front and rear clamping members as soon as the rear projection passes by the lateral edge of the rear clamping member.
It is usually desirable to engage the cleat in the clamping mechanism quickly and to avoid inadvertent disengagement of the cleat from the clamping mechanism. The level of difficulty of engagement and disengagement of the cleat is determined by the biasing force of the spring connected to the pivoting rear clamping member. Thus, quick engagement is accomplished by using a spring having a small biasing force so that the rear clamping member moves easily when the rear cleat projection contacts the vertically inclined portion of the rear clamping member. On the other hand, prevention of inadvertent disengagement is accomplished by using a spring with a large biasing force, thus making it difficult to accidentally pivot the rear clamping member during vigorous riding. In a conventional bicycle pedal such as the pedal described above, there is only one biasing force for both engagement and disengagement of the cleat. Thus, the desired differences in engagement and disengagement forces cannot be accommodated.